In order to adequately test agents in vitro for their radiation modifying capacity, clonogenic assays are necessary. For these assays a number of pieces of equipment are necessary, including incubators, a biosafety cabinet, a cell counter, phase contrast microscope, stereomicroscope, and disposable materials. In addition, a library of cell lines provides the ability to test these agents in cells with appropriate mutations or altered signaling pathways. This year the laboratory has purchased the necessary equipment to begin testing a number of agents. In addition, the laboratory has obtained a number of candidate compounds through agreements with industry, including a PARP inhibitor, a MEK inhibitor, and an antioxidant known to localize to the mitochondria. Finally, equipment and disposables necessary to perform basic laboratory procedures, such as Western blotting, ELISA, PCR, RT-PCR, and immunofluorescence has been obtained to allow an evaluation of mechanisms of radiation modification. In addition, in vivo tumor regrowth delay assays are critical in evaluating the efficacy of these agents in tumors. This is especially important in the setting of agents known to alter tumor physiology but not directly alter biological processes within cells. This year the laboratory has established an animal program through initiation of a number of animal protocols designed to test both radiations sensitizers and radiation protectors, two types of radiation modifiers. These experiments require a significant amount of work with tissue specimens including immunohistochemistry, Western blotting, ELISA, and RT-PCR. Additional equipment and disposables necessary to pass tumors and to perform these mechanistic assays in tumors has been obtained.